As computer systems become increasingly ubiquitous and widespread, there is increasing interest in improving the performance and software execution speed of the computer systems. One of the methods used by designers to increase software execution speed is to increase the processor “clock speed.” Clock speed refers to the rate at which digital systems (graphic processor units, central processor units, digital signal processors, etc.) step through the individual software instructions. For example, with many microprocessor designs, one or more instructions are executed per clock cycle. Increasing the number of clock cycles per second directly increases the number of instructions executed per second.
Another method used by designers is to increase the density of the electrical components within integrated circuit dies. For example, many high-performance microprocessors include tens of millions of transistors integrated into a single die (e.g., 60 million transistors or more). As density increases, the clock speeds possible within a given processor design also increase, for example, as circuit traces are packed ever more closely together.
In addition to increasing the processor software execution speed, another method used by designers to increase computer system performance is to increase the memory clock speed. The memory clock speed generally refers to the rate at which computer system memory (e.g., DRAM, SDRAM, RDRAM, etc.) can accept data from, and provide data to, the other components of the computer system (e.g., the CPU, GPU, etc.).
For example, high-performance memory (e.g., high clock speed memory) is typically used in those computer systems equipped with high-performance, high clock speed, processors. Ideally, the high-performance memory should provide sufficient bandwidth to prevent the processor running out of instructions or otherwise occurring idle time waiting for instructions or data. As with microprocessors, increasing the system memory clock speed directly increases the number of instructions that can be provided to the processor, and thus executed, per second.
Increasing processor clock speed and increasing memory clock speed causes increased power dissipation for the components and an increased amount heat. Accordingly, increasing performance also requires an increase in the efficiency of heat removal from the components. As integrated circuit density increases and clock speed increases, the thermal energy that must be dissipated per unit area of silicon also increases. To maintain high-performance, stable operating temperatures must be maintained. Accordingly, the use of carefully designed heat dissipation devices (e.g., heat sink fans, liquid cooling, heat spreaders, etc.) with high-performance processors has become relatively standardized.
Performance enhancing techniques, such as increased component density, increased clock speed, and increased heat dissipation, are carefully balanced in order to obtain an optimum performance level. Processor circuit density, memory component circuit density, clock frequency, and thermal dissipation are balanced to provide high-performance while maintaining some margin of safety. For example, if a processor or memory components are clocked at too high a frequency, excessive power consumption occurs, leading to overheating. Over heating leads to computational errors, unpredictable behavior, or even physical destruction of processor and/or memory. As more and more functions are integrated into ever more densely packed semiconductor dies, the clock speed can be increased, however, the resulting increased switching activity leads to greater heat generation. These factors are balanced to provide an optimal performance for given device.
There exists particular problems, however, with respect to thermal management of newer types of high-performance memory, such as, for example, DDR II memory. As described above, maximum attainable integrated circuit performance is dependent upon the temperature of the underlying silicon comprising the integrated circuit (e.g., electron mobility, etc.). Generally, for a given semiconductor integrated circuit, cooler semiconductor temperatures yields faster performance (e.g., higher electron mobility) than warmer semiconductor temperatures. This effect is often evidenced in the “jitter” on the rising edges of various signals within a memory component. Performance factors (e.g., clock frequency, component density, thermal dissipation) are typically optimized with respect to expected steady-state operating conditions. This leads to problems when changing temperature conditions are encountered, or where heavy processing loads are encountered.
For example, for DDR-II it is essential to be able to monitor thermal activity of the DRAMs. The high clock speed of DDR II memory will cause rapid temperature buildup if the memory components are continuously accessed under heavy processing loads. The heat generated, if left unchecked, would destroy the component. Thus, what is required is a method for managing the thermal loads incurred by high-performance memory.